As disclosed in Japanese Laid-open Patent Publication 2010-46739, a known screw-tightening power tool comprises a rotary-drive part having, at a front-end part of a housing that houses a motor, a first spindle rotationally driven by the motor and a second spindle configured to hold a tip tool (tool accessory). The rotary-drive part is configured to tighten a screw by transmitting rotational energy from the first spindle to the second spindle when the second spindle is in a retracted position.